The present invention refers to a method and a device for measuring dynamic parameters of particles, e.g. spermatozoa, such as the translation speed and the rotational speed of particles. In addition, also the number of particles can be evaluated.
The present invention is used for establishing parameters related to the dynamics/mobility of particles in a solution, in particular biological entities, e.g. cells and cell organelles including spermatozoa. Analysing the dynamic parameters and number of spermatozoa in semen is of importance in order to characterise spermatozoa, and constitutes an important tool for evaluation of male fertility.
By translation speed (velocity) is meant a directed motion of particles of one or more directions in a detection area or volume such that the path length is significantly longer that the observation length. In contrast to the translation speed there is e.g. Brownian motion signifying stochastic motion of the particles in all directions, i.e. the path length is significantly shorter than the observation length.
A method for determining the motility of spermatozoa is disclosed in U.S. Pat. No. 5,116,125, said analyser being based on dynamic laser light scattering.
Another method for measuring the motility of spermatozoa is to monitor the spermatozoa with a video camera and analyse the movements of the spermatozoa with computer based analysis of individual trajectories. Although this type of computer aided analysis generates fitness parameters rather quickly compared to manual testing, the analysis has several drawbacks particularly a significant variance with respect to the obtained parameters which increases with increased concentration of the spermatozoa.
Object of the present invention is to provide a method and device which provide substantially improved quality of dynamic parameters of particles in a solution. In addition, the particle concentration can also be accurately established. The present invention is specifically advantageous for measuring dynamic parameters of particles in a solution comprising the particles in low as well as in high concentrations.
Other advantages are apparent from the text below.